Manufacture of paper pulp



Patented June 7,1927.

UNITED STATES PATENT OFFICE.

JAMES BROOKES IBEVEBIDGE, 0F RICHMOND, VIRGINIA.

MANUFACTURE or PAPER rum.

No Drawing.

This invention has for its object the utilization of the Waste liquor from sodium acid sulphite pulp process in the manufacture of pulp by the sulphate of soda process.

7 hen wood and other fibrous materials are digested in aqueous solutions of sodium acid sulphite, the waste liquors therefrom contain sodium acid sulphite and sodium sulphonic organic compounds.

In the manufacture of pulp by the sulphate of soda process, losses of chemicals occur in the cycle of digesting the fibrous substances and recovery of the chemicals.

These losses must be made up by the addition of sodium and sulphur compounds in some form. These fresh chemicals are added in the chemical recovery system.

Also in the manufactureof sulphate of soda pulp, it is the eneral practice to charge the digester with c ips, pump in the strong freshly-made alkaline cooking liquor, the volume of which is usually not more than one-half of that required to fill the digester, the necessary volume to cover the chips being made up by the addition of waste black liquor froma previous digestion. 1 My process is tomake up the necessary volume by the addition of the Waste liquor from the sodium acid sulphite process instead of the waste black liquor above mentioned. By the addition of this waste acid sulphite liquor, no fresh chemicalswill need to be added in the chemical recovery and in the preparation of the cooking solutions for the manufacture of sulphate of soda pulp, which is necessary in the present practice of this process, presentin the waste sulphite liquor is suflicient to make up the chemical and mechanical losses of these two elements occurring in the manufacture. The soda salts in the waste black liquor resulting from theabove method of cooking sulphate of soda pulp are then recovered for re-use as is the general practice in the sulphate of soda process.

My invention can be carried out in several ways:

1. After the requisite volume of strong alkaline cooking solution has been pumped into the digester, the volume is made up with waste sodium acid sulphite liquor.

2. To mix the waste liquor from the soas the sodium and sulphur Application filed April 13, 1925. Serial No. 22,884.

dium acid sulphite pulp .with the fresh strong alkaline cooking liquor and then pump the mixture intothe sulphate of soda pulp digester.

3. To pretreat the chips in the sulphate of soda digester with Waste liquor from the sodium acid sulphite pulp and after such pretreatment to drain oil a portion, and then add thestrong alkaline cooking solution in sufiicient quantity to complete the digestion of the fibrousmaterials into pulp.

\Vhat I claim as new is:

1. The method of treating woods and other fibrous substances for the production of pulp which comprises the cooking of the said woods and other fibrous substances in a mixture of sodium hydrate and sodium sulphide in aqueous solution, and of waste liquor obtained from the digestion of woods and other fibrous substances in solution of sodium acid sulphite.

2. The method of treating woods and other fibrous substances for the production tained by digesting woods and other fibrous substances in aqueous solutions of sodium acid sulphite comprising the mixing said waste liquor with solutions' of sodium hydrate and sodium sulphide, and using this mixture for the manufacture of sulphate of soda pulp.

4. In the process of manufacturing paper pulp by the sulphate of soda process, the step ofemploying in the digestor in combination with the liquor used in the sulphate soda process, waste liquor resulting from the digesting of wood or other fibrous material with so ium acid sulphite.

In testimony whereof I hereunto affix my signature.

JAMES BROOKES BEVERIDGE. 

